Pigment Type

Chemical Name

Chemical Formula

Properties

Permanence

Bismuth Yellow has excellent lightfastness.

Toxicity

Bismuth orthovanadate is harmful if swallowed. It is irritating to the eyes, respiratory system, and skin. Exposure may cause conjunctivitis, rhinitis, and reversible irritation of the respiratory tract. More severe cases may cause bronchitis, bronchospasms, and asthma like disease. It may cause polycythemia, red blood cell destruction and anemia, albuminuria and hematuria, gastrointestinal disorders, nervous complaints, and severe cough. However, bismuth vanadium oxide is completely insoluble in water. This limits absorption and biological activity. In waterbased paints, it must be suspended in a binder vehicle. Because of low absorption, such clinical symptons are primarily limited to cases of long-term occupational exposure.

History

Bismuth orthovanadate occurs naturally in several minerals. Although it was synthesized in the 1920s, it was not developed as a commercial pigment until the 1970s.

Alternate Names

PY3—Hansa Yellow 10G

Pigment Type

Chemical Name

n/a

Chemical Formula

C16H12CL2N4O2

Properties

This Hansa yellow is a transparent yellow. It has great brightness and tinting strength and its drying time ranges from average to slow.

Hansa Yellow makes more intense tints and cleaner secondaries than Cadmium Yellows, especially when mixed with other organic or modern colors like Phthalo Blue and Green. Because they are more transparent, they have great value as glazing colors.

Permanence

This Hansa Yellow has fair to good permanence, particularly in the lighter shades.

Toxicity

Hansa Yellow has no significant acute hazards, though its chronic hazards have not been well studied.

History

Hansa Yellows were first made in Germany just before WW1 from a series of synthetic dyestuffs called Pigment Yellow. They were intended to be a synthetic replacement for Cadmium Yellow.

Alternate Names

PY42—Yellow Ochre

Pigment Type

n/a

Chemical Name

iron(III)-oxide, hydrated

Chemical Formula

Fe2O3 • H2O

Properties

Yellow Ochre provides artists with earthtones from cream to brown. It has good hiding power, produces a quick drying paint, and can be safely mixed with other pigments. Its transparency varies widely from opaque shades to more transparent ones, which are valued for their use as glazes. If gypsum is present, Yellow Ochre is not suitable for frescoing. (See Brown Ochre, PY43.) PY42 is made from synthetic iron oxides. PY43 is made from natural iron oxide.

Permanence

Yellow Ochre has excellent permanence because ochres are some of the most permanent pigments available.

Toxicity

Yellow Ochre is non-toxic unless it contains manganese.

History

Ochre comes from the Greek word ochros, meaning pale yellow. It was one of the first pigments to be used by human beings, and evidence of its use has been found at 300,000 year old sites in France and the former Czechoslovakia.